The invention relates to a multiple-fiber optical connector, and method for assembling the multiple-fiber optical connector.
Multiple-fiber optical fiber ribbons in which optical fibers juxtaposed in a plurality are collectively sheathed by a sheathing portion are used as optical transmissions. Further, a multiple-fiber optical connector has been used, in which the optical fibers are exposed by removing the sheathed portion at the tip end side of a multiple-fiber optical fiber ribbon, and the terminal end portion of the multiple-fiber optical fiber ribbon including the exposed optical fibers is inserted and fixed in a ferrule.
Where connecting optical fibers to each other by using an optical connector including such a multiple-fiber optical connector, accurate alignment among the respective optical fiber insertion holes is a requisite technology in order to minimize the connection loss. Further, high production efficiency assembling work with which the ratio of defective occurrence is minimized is also required for multiple-fiber optical connectors.
A prior art multiple-fiber optical connector has a ferrule 1 (multiple-fiber connector body) as shown in FIG. 6 and FIG. 7. A multiple-fiber optical fiber ribbon 31 and the respective optical fibers 32 are inserted and fixed in the ferrule 1. The ferrule 1 is provided with a boot insertion hole 12 into which the terminal end of the multiple-fiber optical fiber ribbon is inserted. Also, a V-shaped groove 21 which guides optical fibers is provided subsequent to said boot insertion hole 12. Further, a minute hole 7 for inserting an optical fiber, which has a slightly greater diameter than that of the optical fiber is provided subsequent to the V-shaped groove 21.
An adhesive agent inserting window 11 is formed on the upper surface of the ferrule 1, and the adhesive agent is used to cement the multiple-fiber optical fiber ribbon 31 and the respective optical fibers 32 to the ferrule 1. The adhesive agent inserting window also functions as a monitoring window for accurately inserting the respective optical fibers 32 into the minute holes 7 for inserting optical fibers.
The assembling process of the abovementioned prior art multiple-fiber optical connectors is as described below; First, after the sheath at the tip end side of a multiple-fiber optical fiber ribbon 31 is removed and the respective optical fibers are exposed (for taking out the heads thereof), a boot 34 is placed on the multiple-fiber optical fiber ribbon. And, the multiple-fiber optical fiber ribbon 31 is inserted into the boot insertion hole 12, and at the same time, the respective optical fibers are inserted into minute holes 7 for inserting optical fibers along the V-shaped groove 21. Next, an adhesive agent is supplied through the adhesive agent inserting window 11 and is filled up in the minute holes for inserting optical fibers while moving the multiple-fiber optical fiber ribbon forward and backward. And, the adhesive agent is thermally hardened, whereby the assembling is completed.
In the prior art multiple-fiber optical connector described above, the position for inserting the inserted multiple-fiber optical fiber ribbon 31 is determined, as shown in FIG. 6(a), at the position where the tip end portion (end face) 33 of the sheathed portion of the multiple-fiber optical fiber ribbon is brought into contact with a stepped portion 22 being the commencing position of the V-shaped groove 21. Further, FIG. 6(a) shows that the tip end portion 33 of the sheathed portion of a multiple-fiber optical fiber ribbon is accurately positioned at the stepped portion 22.
However, there are cases where, due to a slight unbalance in the working conditions, the tip end portion 33 of the optical fiber ribbon mounts the stepped portion 22 as shown in FIG. 6(b) and mounts the upper surface of the V-shaped groove 21. In these cases, an optical fiber is subjected to a local bending, and is seated and fixed by an adhesive agent with a bending stress given thereto. Therefore, a transmission loss is produced at the bent portion, and in the worst case an optical fiber is broken or cut off.
Also, as shown in FIG. 6 and FIG. 7(a), a ferrule 1 structured so that it has an adhesive agent inserting window 11 according to the prior art is asymmetrical in the vertical direction. Therefore, as the adhesive agent is hardened and contracted in an optical connector provided with the ferrule having the abovementioned structure, the surface weak in structure, where the adhesive agent inserting window 11 is provided, is deformed concave as shown in FIG. 7(b).
If such a deformation is produced, in the case of a multiple-fiber optical connector having a wide width, optical fibers whose array position is close to both sides and which are arrayed at the center portion greatly slip in the Y direction in FIG. 7(b) as shown at S is the same drawing. If so, the connection loss of the optical fibers using a multiple-fiber optical connector will be increased.
In addition, where it is assumed that the optical fiber array direction is the X direction, the abovementioned Y direction is orthogonal to the X direction and Z direction of the optical fiber axis. Also, a reference number 13 indicates an inserting hole for fitting pins used to connect an optical fiber to the mating optical connector.
As a countermeasure for deformation of the multiple-fiber optical connector, it is possible that a concave deformation amount of an optical connector resulting from the hardening and contraction amount of the adhesive agent is estimated in advance, and the position of the minute holes for inserting optical fibers is offset in design. However, since the amount of deformation is made uneven in line with an unbalance in the amount of inserting an adhesive agent, it was remarkably difficult to accurately assemble a highly accurate optical connector which can minimize the connection loss.
The invention solves the abovementioned shortcomings and problems, and it is therefore an object of the invention to provide a multiple-fiber optical connector which can facilitate automation of assembling work.
A multiple-fiber optical connector according to the first aspect of the invention is featured in that a multiple-fiber connector having a multiple-fiber optical fiber ribbon in which optical fibers juxtaposed in a plurality are collectively sheathed by a sheathing portion, and having the optical fibers exposed by removing the sheathed portion at the tip end side of the multiple-fiber optical fiber ribbon, in which the terminal portion of the multiple-fiber optical fiber ribbon including the exposed optical fibers are inserted and fixed in a ferrule; wherein the connector is provided with a ribbon insertion hole having a greater width than the width of the multiple-fiber optical fiber ribbon, a tapered portion communicating with the multiple-fiber optical ribbon, whose diameter is decreased toward the tip end side thereof, and minute holes for inserting optical fibers which communicate with the tapered portion and are juxtaposed in a plurality so that the respective exposed optical fibers are individually inserted thereinto, from one side to the other end side in the ferrule; the width at the tip end portion of the tapered portion is formed to be narrower than that of the multiple-fiber optical fiber ribbon; and the position in a width, in the course of the tapered portion, which is roughly coincident with the multiple-fiber optical fiber ribbon stops the tip end portion of the sheathed portion at the terminal portion of a multiple-fiber optical fiber ribbon inserted from the ribbon insertion hole, and is made into a stopping portion of the sheathed portion tip end which determines the tip end position.
A multiple-fiber optical connector according to the second aspect of the invention is featured in that, in addition to a multiple-fiber optical connector as set forth in the first aspect, an optical fiber introducing hole whose diameter is greater than that of minute holes for inserting optical fibers is formed at the forward side at the tip end side of the tapered portion, a conical inlet portion whose diameter is reduced is formed at the tip end side of the optical fiber introducing hole, and minute holes for inserting the optical fibers are formed so as to communicate with the conical inlet portion.
A multiple-fiber optical connector according to the third aspect of the invention is featured in that, in addition to a multiple-fiber optical connector as set forth in the first aspect or the second aspect, instead of forming a tapered portion whose tip portion width is narrower than the width of a multiple-fiber optical fiber ribbon, the connector is provided with a first tapered portion whose tip end width is roughly coincident with that of the multiple-fiber optical fiber ribbon, a tip end side insertion portion of a sheathed portion, which communicates with the first tapered portion, having a roughly fixed diameter, and whose hole width is roughly coincident with the multiple-fiber optical fiber ribbon, and a second tapered portion having a diameter-reduced tip end portion formed, via a stepped portion, at the tip end of the tip end side insertion portion of the sheathed portion; the inlet diameter of the second tapered portion is formed smaller than the width of the multiple-fiber optical fiber ribbon; the stepped portion of the tip end of the tip end side insertion portion of the sheathed portion stops the tip end portion of the sheathed portion at the terminal end portion of the multiple-fiber optical fiber ribbon, and is made into the sheathed tip end stopping portion which determines the position of the tip end portion.
A multiple-fiber optical connector according to the fourth aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the third aspect, a conical introduction portion having a diameter-reduced portion at the tip end thereof is formed at the outlet of the tapered portion.
A multiple-fiber optical connector according to the fifth aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the third aspect, a conical introduction portion having a diameter-reduced reduced portion at the tip end thereof is formed at the outlet of the second tapered portion.
A multiple-fiber optical connector according to the sixth aspect of the invention is featured in that, in addition to a multiple-fiber optical fiber according to the fourth aspect, the respective input end diameters of the conical introduction portion are formed so as to become L greater than D greater than 1xc3x97sin xcex8, where the optical fiber array pitch of a multiple-fiber optical fiber ribbon is L, the length of exposed optical fibers at the tip end of the multiple-fiber optical fiber ribbon is 1, the deflection angle of the exposed optical fibers is 0, and the respective inlet diameters of the conical introduction portion are D.
A multiple-fiber optical connector according to the seventh aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the fifth aspect, the respective input end diameters of the conical introduction portion are formed so as to become L greater than D greater than 1xc3x97sin xcex8, where the optical fiber array pitch of a multiple-fiber optical fiber ribbon is L, the length of exposed optical fibers at the tip end of the multiple-fiber optical fiber ribbon is 1, the deflection angle of the exposed optical fibers is xcex8, and the respective inlet diameters of the conical introduction portion are D.
A multiple-fiber optical connector according to the eighth aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the first aspect or the second aspect, no insertion window for an adhesive agent is provided.
A multiple-fiber optical connector according to the ninth aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the third aspect, no insertion window for an adhesive agent is provided.
A multiple-fiber optical connector according to the tenth aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the fourth aspect, no insertion window for an adhesive agent is provided.
A multiple-fiber optical connector according to the eleventh aspect of the invention is featured in that, in addition to a multiple-fiber optical connector according to the fifth aspect, no insertion window for an adhesive agent is provided.
A multiple-fiber optical connector according to the twelfth aspect of the invention is featured in that, in addition to the sixth aspect or the seventh aspect, no insertion window for an adhesive agent is provided.
A method for assembling a multiple-fiber optical connector according to the invention is an assembling method described in any one of either the eighth aspect through the twelfth aspect, wherein the terminal end portion of the multiple-fiber optical fiber ribbon including exposed optical fibers is fixed in a ferrule by hardening an adhesive agent after inserting the adhesive agent into the inlet side of a ribbon insertion hole of the ferrule, absorbing the adhesive agent through the outlet side at the tip end of the minute holes for inserting optical fibers, and inserting the exposed optical fibers into the minute holes for inserting optical fibers with the sheathing at the tip end of the multiple-fiber optical fiber ribbon removed.
A multiple-fiber optical connector according, to the first aspect or the second aspect of the invention is constructed so that a tapered portion which is diameter-reduced toward the tip end is provided at a ribbon inserting hole having a greater width than that of the multiple-fiber optical fiber ribbon, and the position, in the course of the tapered portion, of a width roughly coincident with the width of the multiple-fiber optical fiber ribbon stops the tip end portion of the sheathed portion of the terminal portion of the multiple-fiber optical fiber ribbon inserted from the ribbon inserting hole, and is made into a sheathed portion stopping portion which determines the tip end portion position.
Thus, in a multiple-fiber optical connector according to the first aspect or the second aspect of the invention, since the position of the tip end portion of the sheathed portion of the terminal end portion of the multiple-fiber optical connector is determined, there is no case where the tip end portion of the sheathed portion of the multiple-fiber optical connector mounts the stepped portion formed in the ferrule. Therefore, the multiple-fiber optical connector according to the first aspect or the second aspect of the invention can completely prevent mistakes in operation from occurring, such as a positional slip of the sheathed portion which will cause a transmission loss, an accident of interruption, etc.
Further, since a multiple-fiber optical connector according to the first aspect of the invention is simpler in structure, it becomes easier to produce the multiple-fiber optical connector itself. Also, in the multiple-fiber optical connector according to the second aspect, since minute holes for inserting optical fibers are formed via the optical fiber introducing holes and conical inlet portions having a reduced diameter at the tip end, it is possible to further easily carry out insertion of exposed optical fibers of the multiple-fiber optical fiber ribbon.
In a multiple-fiber optical connector according to the third aspect of the invention, there are provided the first tapered portion having a reduced diameter at the tip end, the tip end insertion portion at the sheathed portion, whose hole diameter is roughly coincident with the width of the multiple-fiber optical fiber ribbon and is roughly made fixed, and the second tapered portion having a reduced diameter at the tip end, which is formed at the tip end of the tip end insertion portion of the sheathed portion via the stepped portion, wherein the stepped portion at the tip end of the tip end insertion portion of the sheathed portion is made into a stopping portion of the tip end portion of the sheathed portion at the terminal end portion of the multiple-fiber optical fiber ribbon.
Therefore, the multiple-fiber optical fiber ribbon inserted into the ferrule can be positioned at an appointed position with respect to not only positioning in the insertion direction but also positioning in the vertical and horizontal directions without slipping from the center axis.
A multiple-fiber optical connector according to the fourth aspect or the fifth aspect of the invention is provided with a conical introducing portion formed at the outlets of the tapered portion and the second tapered portion, whereby it is possible to very easily perform insertion of exposed optical fibers.
In a multiple-fiber optical connector according to the sixth aspect or the seventh aspect of the invention, the inlet end diameter of the conical introducing portion can be set to an adequate value, and it is possible to further easily insert the exposed optical fibers. In addition, it is possible to collectively insert the exposed optical fibers in the respective corresponding optical fiber insertion holes. Still further, insertion of the terminal end portion of a multiple-fiber optical fiber ribbon including the exposed optical fibers into a ferrule can be securely automated.
In a multiple-fiber optical connector described in any one of either the eighth aspect through the twelfth aspect of the invention, since no adhesive agent inserting window is provided, it is possible to make the structure of an optical connector symmetrical in the vertical and horizontal directions. Therefore, even though the inserted adhesive agent is hardened and contracted, it is possible to prevent concave deformation from occurring, which was produced in prior art optical connectors having an adhesive agent inserting window, and it is possible to propose optical connectors which can minimize the connection loss after the assembling.
A method for assembling a multiple-fiber optical connector according to the invention enables insertion of an adhesive agent in a multiple-fiber optical connector not having any window for inserting an adhesive agent, and the insertion can also be automated. Therefore, it is possible to automate a series of assembling works of optical connectors from insertion of an adhesive agent, insertion of a multiple-fiber optical fiber ribbon, and fixing of the multiple-fiber optical connector in a ferrule by hardening of the adhesive agent.